The present invention relates to a circuit board and a method for making a circuit board and, more particularly, to a method for making a multi-layer electronic- circuit board having apertures which are formed through metal portions of the board and which may be selectively connected and/or detached from an electrical ground plane.
Multi-layer circuit boards allow electronic and/or electrical components to selectively and operatively populate opposed top and bottom surfaces of each board (or other respective interior portions of each of the boards), thereby desirably allowing each of the electronic and/or electrical circuit boards to contain a relatively large amount of electronic components which efficiently and densely populate the respective boards. It is desirable to allow each of the components containing surfaces or portions of a created and/or formed electronic and/or electrical circuit board to communicate, thereby allowing the contained electronic components on each side of the board (or within certain interior portions of the board) to cooperatively and selectively form one or more desired electronic circuits. This communication may require the use of shared electrical ground planes, the transmittal of power and/or control type signals between each of the component containing surfaces or board portions, and/or the connection of components on each of the opposed surfaces and/or within and between certain of the interior portions and the top and/or bottom board surfaces.
This desired interconnection typically requires that one or more holes be drilled through each of the circuit boards, thereby physically creating at least one xe2x80x9cthrough holexe2x80x9d or xe2x80x9cviaxe2x80x9d lying between each of the opposed component containing surfaces and through the various interior circuit board portions. Such drilling is undesirable since it is relatively time consuming, costly, potentially causes damage to significant numbers of the formed electronic circuit boards requiring these circuit boards to be destroyed, and requires costly and inefficient electroless and/or electrolytic plating of the formed holes or xe2x80x9cviasxe2x80x9d.
While some attempts have been made to obviate the need for such plating, such as by the use of a conductive epoxy within each of the drilled holes, these attempts have not produced reliable electrical interconnections and these produced interconnections are not typically adapted to allow the communication of electrical power signals between the board surfaces or to securely and reliably receive a component.
Further, it is desirable to form xe2x80x9cair-bridgesxe2x80x9d or xe2x80x9ccrossover type circuitsxe2x80x9d upon one or more selected surfaces and/or within certain component containing portions of the formed circuit board in order to allow multiple levels of circuits and/or electrical interconnections to be formed upon a single board surface and/or within a certain component containing portion of the circuit board, thereby desirably increasing the amount of electronic circuits which may be created upon and/or within the created circuit board (e.g., increasing the density of the contained electronic circuitry).
These xe2x80x9cair-bridgesxe2x80x9d or crossover circuits are typically formed by rather complicated, costly, and time consuming processes. The formed bridges and crossover circuits further do not typically and efficiently accommodate certain desirable circuit board interconnection processes, techniques, and/or methodologies such as and without limitation, the use of relatively heavy wire bonding (e.g., aluminum wire having a diameter of about five to about twenty millimeters) or the direct connection of components to a surface of the board.
There is therefore a need to provide a method for producing a multi-layer electronic circuit board which overcomes some or all of the previously delineated drawbacks and which selectively allows grounded and non-ground xe2x80x9cviasxe2x80x9d to be desirably and selectively formed.
It is a first object of the present invention to provide a method for producing a multi-layer electronic circuit board which overcomes some or all of the previously delineated drawbacks of prior multi-layer electronic circuit board forming methodologies and techniques.
It is a second object of the invention to provide a method for producing a multi-layer electronic circuit board which overcomes some or all of the previously delineated drawbacks of prior multi-layer electronic circuit board forming methodologies and techniques and which allows for the selective, efficient, and reliable formation of metallized apertures which allows for communication by and between various portions of the formed multi-layer electronic circuit board and which is further adapted to selectively and communicatively receive an electronic component.
It is a third object of the invention to provide a method for producing a multi-layer electronic circuit board which overcomes some or all of the previously delineated drawbacks of prior multi-layer electronic circuit board forming methodologies and techniques and which allows for the selective formation of metallized apertures which may be selectively connected or disconnected from a selectively formed electronic ground plane or bus.
According to a first aspect of the present invention a multi-layer electric circuit board is provided comprising a first electrically conductive member having a first and a second surface, having a first aperture with a first interior surface, and having a second aperture with a second interior surface; a dielectric material which is applied upon certain portions of the first and second surfaces, and which is applied upon the first interior surface within the first aperture; a first circuit assembly having a second electrically conductive member which is coupled to the dielectric material resident upon the first surface of the first electrically conductive member, the first circuit assembly further including a third electrically conductive member and a first core member which is contained between the second and the third electrically conductive members and which includes at least one air-bridge; and a second circuit assembly having a fourth electrically conductive member which is coupled to the dielectric material resident upon the second surface of the first electrically conductive member, the second circuit assembly further including a fifth electrically conductive member and a second core member which is contained between a fourth and fifth electrically conductive members and which includes at least one air-bridge, the second circuit assembly cooperating with the first circuit assembly and with the dielectric material and with the first electrically conductive member to form a multi-layer circuit board.
According to a second aspect of the present invention a circuit assembly is provided. The circuit assembly is made by the process of providing an electrically conductive core member having at least one selectively formed aperture within the core member; attaching a dielectric adhesive material upon the core member; providing at least one pre-circuit assembly having a second electrically conductive member; attaching the at least one pre-circuit assembly to the dielectric adhesive material which is disposed upon the core member; and selectively etching the second member effective to extend the at least one aperture through the second member and forming a circuit board assembly.
These and other objects, aspects, and advantages of the present invention will become apparent upon reading the following detailed description in combination with the accompanying drawings.